<b-stepper value="0"></b-stepper>
<script>
  const stepper = document.querySelector('b-stepper');

  function handleChange(event) {
    if (event.composedPath()[0] === stepper) {
      const eventDetail = event.detail;
      window.BMessage.info({ content: 'current stepper value：' + eventDetail.value });
    }
  }

  stepper.addEventListener('change', handleChange);
</script>
